Scale Model Solar System!

[Scale Model Sun]Scale Model Sun

There is a lot of space between the planets in our solar system. To show this, we've laid out a scale model solar system on our tour. We've scaled the size of the tour's solar system by setting the 100 meter diameter of the Green Bank Telescope (currently under construction) equal to the diameter of the earth's orbit around the Sun. On this scale, the entire Earth is only a tiny dot, 1/6 inch in diameter. The giant planet, Jupiter, is just under two inches across. The Sun is a ball one and a half feet across.

[Tour Map] The location of the planets on our tour are shown in our map (left). The map is also available in g-zipped postscript format.

It takes radio waves (and all light) 8 minutes to travel from the Sun to Earth. In our scale model, kids can run the 50 meter distance from Sun to Earth in under 8 seconds, or 60 times the speed of light in "real" size scale.

[Mercury] Mercury [Radar image of Mercury]Radar Image

Mercury is the closest planet to the Sun. Because it has virtually no atmosphere (its gravity is so low that it cannot hold gases and liquids to its surface), Mercury has very extreme temperature variations. The planet tour image shows the cratered surface of Mercury based on Mariner Satellite images combined with an NRAO VLA false color image of the planet's surface. A g-zipped postscript version of the Mercury image is also available.

The radar image was produced in a 1991 Jet Propulsion Lab (JPL) Goldstone plus NRAO-VLA (Very Large Array) doppler radar experiment. Red areas show regions of the highest reflectivity; the northern red spot is due to water-ice resting in permanent shade on Mercury's pole. The origin of the other red (highly reflective) areas remain a mystery.

[Venus] Venus

The whitish glow of Venus is caused by thick clouds of sulfuric acid swirling above its carbon-dioxide rich atmosphere. With surface temperatures rising to 450 degrees Celsius (842 degrees Fahrenheit), Venus is pictured here using data from the 1991 Magellan orbiter. A g-zipped postscript version of this Venus image is also available.

[Earth] Earth [Radio image of Moon] Moon Radio Image

Our planet is 71 percent ocean and houses over 1.75 million living species. A g-zipped postscript version of this Earth image is also available.

The radio image of the moon was made using NRAO's 140ft telescope in Green Bank, West Virginia. Our unusally large moon (its diameter is roughly one-fourth that of Earth's) orbits us at 236,000 miles away, on average. This image shows the moon in radio wavelengths, with blue colors representing colder areas of the moon and red colors representing the warmer areas of the moon. The Moon is heated by the Sun and the redder region was facing the Sun at the time of observation.

[Mars] Mars [Radar image of Mars] Mars Radar Image

Mars' rocky surface is cold enough to support polar carbon-dioxide ice caps for part of the year. Its two irregularly-shaped moons are theorized to be gravitationally captured asteroids from the nearby asteroid belt. This Hubble picture shows the Martian surface and Mars' moons. A g-zipped postscript version of this Mars image is also available.

This 1988 Goldstone-VLA radar image of Mars is courtesy of the National Radio Astronomy Observatory. Like the radar image of Mercury, the red areas represent surfaces of high reflectivity. The red regions in the center of the planet are associated with the giant volcanoes located there.

[Jupiter] Jupiter [Radio image of Jupiter] Jupiter Radio Image

Jupiter is more massive than all of the other planets put together. The famous Great Red Spot on Jupiter's side has wind speeds approaching 250 miles per hour. This Hubble Space Telescope (HST) image shows Jupiter and one of its moons, Io. A postscript version of this Jupiter image is also available.

The radio image is from observations with NRAO's Very Large Array (VLA), which shows Jupiter's rings which are difficult to detect optically.

[Saturn] Saturn [Radio image of Saturn] Radio Image

Known mostly for its highly visible rings, Saturn also has more moons than any other planet in the solar system (at least 22 are known). This image shows the relationship between Saturn's size and its moons' sizes, as well as a diagram of divisions in Saturn's ring system. A g-zipped postscript version of this Saturn image is also available.

The radio wavelength image from NRAO's VLA shows Saturns rings scatter and/or absorb the thermal emission from saturns surface.

[Uranus] Uranus

Unlike all the other planets in the solar system, Uranus spins on its side like a wheel instead of spinning "upright" like a top. The 17 moons orbiting Uranus are named for characters in Shakespeare's plays. This image shows Uranus' recently (1977) discovered rings. A g-zipped postscript version of this Uranus image is also available.

[Neptune] Neptune

Discovered only when Uranus' orbit conflicted with the calculated one due to Neptune's gravitational pull, this deep blue planet is composed mostly of hydrogen (74%) and helium (25%). Its color comes from methane in its atmosphere. This image shows Neptune's great dark spot (similar to Jupiter's Red Spot) and its largest moon, Triton. A g-zipped postscript version of this Neptune image is also available.

[Pluto] Pluto

Pluto and Charon have the highest moon-planet size ratio in the entire solar system. They take roughly 247 years to circle our Sun and have never been photographed at high resolution or visited by spacecraft. A g-zipped postscript version of this Pluto image is also available.

[Giacobini-Zinner Comet] Giacobini-Zinner Comet.

Giacobini-Zinner is barely visible in this photo (click on this image to get a larger version and look between the white-pointer lines on the right side of the photo), which may give you some idea of how far away it is from Earth! Discovered in 1900, this comet will come closest to the sun (perihelion) on November 21, 1998 at a distance of 1 A.U. (1 Astronomical Unit=93 million miles!) This photo was taken by Nick James on July 1, 1998.

[Stonehouse Comet] Stonehouse Comet.

Comet Stonehouse was first observed April 22, 1998 by Patrick Stonehouse. After reporting his findings to the Central Bureau for Astronomical Telegrams, astronomer Alan Hale (co-discoverer of Comet Hale-Bopp) confirmed the comet on April 26th. This photo was taken by Tim Puckett on April 27, 1998.


The National Radio Astronomy Observatory (NRAO) is a NSF-funded research organization.

We thank Calvin J. Hamilton for on-line planet photos.
Last update: 01 August 22